TechDemoSat-1 to fly new subsystem designs

TechDemoSat-1 will fly eight innovative and fascinating payloads, but it will also fly some advanced new subsystems developed by SSTL.

All new technologies need to gain flight heritage, and this UK mission which is part funded by the Technology Strategy Board and the South East England Development Agency (SEEDA), was conceived to do just this – demonstrate advanced technologies in space.

Space technology is evolving at a remarkable pace, and our subsystems are no exception. We actively develop “new ways of doing things” to allow our subsystems to do more. What makes us different is that we believe that our products should be designed to push the same design envelope again and again so they deliver more value whilst remaining just as cost-effective and reliable. In the case of subsystems, this also means making sure they remain compatible with existing satellite platforms and interfaces.

Procyon is a new star tracker (each star tracker model is named after a different star) to fly on TechDemoSat-1. A star tracker is an optical device that determines the attitude of a satellite by comparing stars in its field of view to an on-board database called its ‘star catalogue’ to work out which way it is facing, and to track the changes in attitude as the satellite orbits. The Procyon star tracker is for missions requiring cost-effective, medium-resolution attitude determination. Its Camera Head Unit has been upgraded from past models to include Active Pixel Sensor technology, (an image sensor consisting of an integrated circuit containing an array of pixel sensors, each pixel containing a photodetector and an active amplifier) which provides higher resolution data at a low-cost which was trialled on SSTL’s UK-DMC2 satellite.

In addition to its tracking capability, the Procyon offers excellent rate estimates as well as a ‘lost in space’ capability – with no initial attitude determination information, it can be turned on and figure out where it is in the sky. Securing early flight heritage for the Procyon star tracker will also benefit the development of Rigel-L, SSTL’s high-resolution attitude determination star tracker, as both will fly a common Data Processing Unit, a miniaturised version of SSTL’s standard on-board computer. The Rigel-L DPU will go on to gain flight heritage on a further 4 upcoming missions, a medium resolution satellite for Kazakhstan, and for the DMC3 constellation of 3 high resolution satellites for DMCii.

The newly developed SGR-ReSI will also fly on TechDemoSat-1. Adapted from our SGR range of GNSS receivers, the SGR-ReSI is a remote sensing instrument that uses reflected GPS signals, a by-product of GPS navigation, to gain information about ocean, land and ice surfaces. On board TechDemoSat-1, the SGR-ReSI will be used, along with an altimeter from SSTL’s Sea State payload, to measure sea state by capturing signals reflected off the surface of the ocean. The SGR-ReSI will also be flown on NASA’s Cyclone Global Navigation Satellite System (CYGNSS) mission to improve extreme weather prediction by measuring ocean roughness and wind speed. In addition to GPS, the receiver is equipped with multiple frequency readiness so that it is compatible with signals from the Galileo and Glonass navigation systems.

The Subsystems Microsite has more details on the latest subsystems and what they are being used for.